Based on expected Science Drivers for a 60 to 100-m diameter OWL-class telescope, we derive the basic instrumental capabilities that are needed to address them effectively. They come in three flavors -viz. an extremely high-contrast fully diffraction-limited spectro-imager, a cryogenic AO-assisted imager and multi-integral field spectrometer. Their highest priority wavelength range lies in the near-IR. In terms of size and technical requirements, these instruments belong to a quite similar class than instruments currently being developed for the 8-10 m telescopes. This places them hopefully in the feasible category, even if already rather challenging. A big caveat however is that enlarging the imaging field or the spectrometer multiplex would require large clusters of these basic “bricks”. The requirements on the adaptive optics correction are stringent and call for a close and careful integration between the telescope adaptive optics systems and the instruments. We also introduce here, as a relevant example of a new observational strategy, an instrument focused on a specific scientific program - the direct measurement of the acceleration of the Universe at different epochs via the Lyα forest in QSO spectra. Being able to host dedicated facilities of this type, used for a specific observing programs in a CERN experiment-like fashion, is deemed essential to ensure that the giant telescopes of the future get and stay at the cutting edge of research in the next decade and beyond. Finally, we comment briefly on the articulation between the development of generic instrument concepts for ELTs in the frame of the European ELT Design Study and their adaptation to the OWL case.